Printing plate clamping mechanism



Oct. 28, 1958 E. w. WORTHINGTON ETAL 2,857,841

PRINTING PLATE CLAMPING MECHANISM Filed March 9. 1953' I s Sheets-Sheet 1 IN V EN TOli.

BY Car/17. Eg

Oct. 28, 1958 E. w. wofifi-llNe'roN ETAL 2,857,341

I PRINTING PLATE CLAMPING; MECHANIM Filed March 9, 1953 s Sheets-Sheet 2 E W W I Z Q I710) of z y a I y Oct. 28,1958 E. w. WORTHINGTON EIAL 357, PRINTING PLATE CLAMPING MECHANISM Filed March 9. 1953 3 Sheets-Sheet 3 3s 55 ,8 s3 35 6 6o 2 II N 6 4 3 INVENTOR.

Emory Worl@fon BY Car/15C Bfiye United States Patent PRINTING PLATE CLAMPING MECHANISM Emory W. Worthington, Hastings-on-Hudson, and Carl H. Ringe, White Plains, N. Y., assignors to R. Hoe & Co., Inc., New York, N. Y., a corporation of New York Application March 9, 1953, Serial No. 341,026 7 Claims. (Cl. 101-378) This invention relates to printing plate clamping mechanisms, and, more particularly, to mechanisms of the type which hold a stereotype plate on a printing cylinder by means of hooks engaging in recesses in the underside of the plate.

It is an object of the invention to provide an improved clamping mechanism of the type indicated, and which is of an exceptionally simple and compact character.

A further object is to provide a clamping mechanism of the type indicated, in which clamping units may be operated in unison, but in which the clamping action of any unit may be substantially independent of the others.

With these and still other objects which will appear in the following full description in mind, a plate clamping mechanism embodying the invention in a preferred form will now be described with reference to the accompanying drawing, and the features forming the invention will then be pointed out in the appended claims.

In the drawing:

Figure 1 is a schematic plan view of a printing cylinder including the clamping mechanism of the invention;

Figure 2 is a fragmentary plan view, similar to Figure l, but showing the clamping mechanism rearranged to take printing plates of a different size;

Figure 3 is a fragmentary end elevation of the cylinder on an enlarged scale;

Figure 4 is a plan view on an enlarged scale, showing two of the clamping units forming part of the clamping mechanism;

Figure 5 is an enlarged elevation of certain parts of the clamping unit, shown as removed from the unit to bring out more clearly the construction;

Figures 6 and 7 are schematic elevations, showing essentially the mechanism of Figure 5, and in clamping and unclamping position respectively;

Figure 8 is a section on the line 8-8 of Figure 4;

Figure 9 is a section similar to Figure 8, but showing the parts in a different position;

Figure 10 is a section on the line 1010 of Figure 4; and

Figure 11 is a section on the line 11-11 of Figure 8.

The cylinder structure is generally of the type shown in prior Harless application Serial No. 290,940 filed May 31, 1952 for Printing Plate Cylinder, now U. S. Patent No. 2,708,875.

The cylinder 1 carries a number of plates 2, the outlines of which are indicated in phantom in Figure 1. As usual, the cylinder illustrated may carry a total of eight plates, arranged four across and two around the cylinder, and the plates at one end of the cylinder being staggered or angularly displaced with reference to plates at the other end of the cylinder, for reducing vibration in printing. A number of plate clamp units 3 and spacer blocks 4 are provided, and the plate clamp units are operated in groups of four by means of shafts 5, the ends of which project out from the ends of the cylinder and are provided with a mechanism indicated generally at 6, for

turning them from clamping to unclamping position, or vice versa.

The cylinder is provided with generally rectangular axial grooves or channels 7, having axial dovetailholding grooves 8 formed in their radially inward or bottom surfaces. Bores 9 (Figure 8) communicating withthechannels 7 to one side thereof, accommodate the operating shafts 5.

The operating mechanism comprises, for each shaft'5, an arm 10 fixed to the shaft, alink 11 pivotally connected to the end of the arm 10 and also pivotally connected to an arm 12 rotatably fixed to the cylinder end. An'extension 13 of the arm 12. has a socket 14 for takinga wrench 15.

In Figure 3, the operating mechanism associated with the shaft 5 is shown in full. lines in the plate clamping position, While the unclamping. or releasing position is indicated in phantom. Motion toward plate clamping position is limited by a stud 16 against which an adjustable stop screw 17 abuts in the clamping position, and against which the extension 13 of arm 12 abuts in. the unclamped position. A spring pin 19 on the underside of the arm extension 13 engages a recess formed in the cylinder in alignment with the pin, when the operating mechanism is in the clamped position, andanother recess 18, serves to hold. the mechanism when the parts are moved to the unclamped position.

The clamping assemblies 3 are. adjustably fixed inthe channel or groove 7, as later described in detail, and may be rearranged as indicated in Figures 1 and 2 for taking plates of different widths, the spacer blocks 4 beingrelocated accordingly.

Each clamping unit 3 comprises a frame structure or block composed of a lower member 25 and upper members 26 and 27 fastened. thereto by means of bolts 28. Member 25 is cut away at 30 so as to continue the cylindrical bore 9 and is further recessed and bored to take the hooks or clamps of the operating mechanism described below.

Bolts 31 passing. through bores in the members 25 and 26 are countersunk below the cylinder surface and have their threaded ends engaged in correspondingly threaded bores in dovetail blocks 32 slidably fitting in the dovetail grooves 8, so that the. clamping unit may be fastened in position in any desired location along the channel 7 by tightening the bolts 31, but may be adjusted along the channel or removed therefrom by loosening or unscrewing the bolts 31.

A shaft 33 carried in the member 25 and held therein by set screws 34 provides a rotatable mounting for plate clamp hook arms 35 and a hook operating member 36. The hooks 35 are positioned to each side of the member 36 and have abutments 37 positioned for engagement by an axially extended lug 38 formed on the member 36, which overlies the hubs of the hooks 35 so as to be engageable by the hook lugs 37.

The adjacent ends or faces of the hooks 35 and member 36 are recessed to take torsion springs 40, one end of these springs being received in slots or grooves 42 in the member 36, as indicated. The faces of the hook members 35 facing the member 36 are similarly recessed to accommodate the torsion springs 40 and are similarly provided with grooves 43 for taking the other ends 44 of the springs. The springs tend to force the hooks in one direction (clockwise or toward clamp.- ing position), and the member 36in the opposite direc-. tion, this movement being limited by the engagement of the lugs 37 with the lug 38. Member 36 is also formed with a fork 45, supporting a shaft 46 carrying a rotatable roller 48, and secured to the fork by'set screws 47.

-hooks is prevented.

The movement toward and from clamping position is accomplished by rotating or turning the shaft 5. In the unclamped or retracted position of the hooks, the roller 84 is accommodated in a groove 50 on shaft 5, while the lug 38 is engaged by an abutment 51 at one end of a second groove or recess 52. A cam rise 53 for pushing the hooks toward clamping position by means of the roller 48, and a high dwell 54 for holdmg it in such position are also provided. In moving the hooks from the retracted to clamping position, the shaft 5 is rotated (counter clockwise), the rise 53 acting on roller 48 to rotate the assembly 3536 toward clamping position. Abutment 51 is simultaneously cleared out of the way of the lug 38 so as to permit this movement. The assembly 35-36 moves bodily and as a unit until the hooks 35 engage in the recesses under the plate, at which time further movement of the Thereafter, the cam shaft actlng on the roller 48 rotates the member 36 about the shaft 33, separating lugs 37 and 38, so that the pressure of springs 40 is applied against the hooks 35. Springs 40 are prestressed to the desired clamping pressure and are readily constructed so that the maximum amount of movement involved between members 35 and 37 will not materially affect the spring torque. The total rotation of hooks 35 with reference to member 36 need 'be only a few degrees, and the actual variation in the forcing it back circumferentially and breaking it loose from the cylinder to permit ready removal.

The clamping unit also incorporates a second pair of hooks or clamps 60 for holding a plate edge. These are formed on a bar 61, the bar being received in a recess 62 in the member 26 and the hooks protruding outwardly through openings in this member. Bar 61 is slidable on the outer surface of member 25, being held thereon by cooperating surface 63 of the member 26, and is urged (to the right of the figure) in a direction opposite to the clamping direction, by a pair of spring pressed plungers 64. A poppet or round pivot block 65 fits in a central bore in the member 61. A threaded cross bore in the poppet receives a correspondingly threaded shank of an adjusting screw 66, the end of the screw 66 abutting against block member 25 at point 67. Screw 66 is provided with a head 68, having radial cross bores to take a wrench or rod. By turning screw 66, the circumferential position of the member 61 may be varied for registering the plate. At the same time, the member 61, and, hence, the hooks 60 carried by it are permitted to pivot about the poppet 65, so that both books 60 may engage solidly, even though one of the recesses in which they engage is slightly out of alignment with the other. By adjusting the two blocks 61 carrying the hooks for a single plate into different circumferential positions, provision is made for mounting a plate in a slightly skewed or cocked position, the blocks automatically adjusting themselves about their poppets 65 so as to align all four units along a slanted or slightly helical line with respect to the cylinder. The surface 25A of member 25 on which the element 61 slides, forms a chordal plane at right angles to an axial plane through the engaging tips of the hooks 60 in an intermediate position of adjustment. Accordingly, the radial component of movement of the hooks due to adjustment of the member 61 or due to its pivoting on the poppet 65 will be to all intents and purposes negli- 4 l gible. Full accommodation for the skewing or cocking of a plate is also obtained while maintaining the ends of the hooks 60 engaged under a plate in alignment along a straight but slightly skewed line, so that solid engagement of the hooks is provided in all positions of adjustment.

With the usual arrangement utilizing a pair of nearly semi-cylindrical plates around a cylinder, the clamping arrangement 3 will be reduplicated on the opposite side of the cylinder and the corresponding parts will be located symmetrically with respect to the cylinder axis. Thus a pair of hooks 35 under one straight edge of the plate and a pair of hooks 60 under the other straight edge of the same plate will cooperate to hold it on the cylinder.

While the plate clamping arrangement of the invention is not limited to use with any particular type of printing machine, it is particularly adapted to use with so called arch type printing machines, in which a pair of impression cylinders are arranged side by side and level with each other, with their cooperating plate cylinders positioned outwardly and below the impression cylinders, the plane joining the axis of a plate cylinder to its cooperating impression cylinder being typically disposed at about 40 to the horizontal. In such arrangements, slightly over 180 of plate cylinder surface is available between the line of impression and the form rollers cooperating with the plate cylinder, which is a sufiicient distance to permit hanging a plate on a pair of hooks 60 and engaging and clamping its other end by a pair of cooperating hooks 35. It will be noted that the plate loosening 0r dislodging fingers do not interfere with this operation. When it is desired to adjust the registry, the end of the plate held by the book will be normally rotated backwardly somewhat from the impression line to permit insertion of a bar or wrench in the screw head 68 for adjusting the hooks 60. In this position, the wrench inserted in the arm extension 13 may be approximately horizontal in locked position and somewhat above vertical in unlocked position. The pressman is thus able, in adjusting for registry, to jog the plate by working the wrench so as to cause fingers 55 to press against the end of the plate thus assisting in adjusting the hook 60 of the cooperating clamping unit 3 in the one direction, or to apply clamping pressure to the hooks 35 by means of the wrench to assist in adjustment in the other direction. In the same way, by working the wrench, the pressman is enabled to Work the plate into a skewed position, whenever the hooks 60 are adjusted for such a position of the plate.

What is claimed is:

1. In a printing plate cylinder, plate clamping mechanism comprising a plurality of clamping units for holding the straight edge of a plate, each unit comprising a hook arm for engaging in a recess in the underside of a plate, an operating member, a shaft mounting the hook arm and operating member for angular movement together and for angular movement relative to each other about a common axis, abutments on the arm and operating member for limiting relative angular movement between them, a torsion spring acting between the arm and operating member to force the abutments together, and an operating mechanism acting upon the operating member at a point spaced from the said shaft axis, for moving the operating member and hook arm bodily about the said axis to engage the hook in a plate recess and operable for further moving the operating member to separate the said abutments and apply pressure through the torison spring to the hook arm.

2. In a printing plate cylinder, plate clamping mechanism comprising a plurality of clamping units for holding the straight edge of a plate, each unit comprising a hook arm for engaging in a recess in the underside of a plate, an operating member, a shaft mounting the hook arm and operating member for angular movement together and for angular movement relative to each other about a common axis, abutments on the arm and operating member for limiting relative angular movement between them, a torsion spring acting between the arm and operating member to force the abutment together, and a common operating mechanism acting upon the operating members of the said plurality of clamping units along a line spaced from the said axis, for moving the operating members and hook arm of each unit bodily about the said axis to engage the hook in a plate recess and operable for further moving the operating member to separate the said abutments and apply pressure through the torsion spring to the hook arm.

3. In a printing plate cylinder, plate clamping mechanism comprising a plurality of clamping units for holding the straight edge of a plate, each unit comprising a pair of hook arms for engaging in recesses in the underside of a plate, an operating member, a shaft mounting the hook arms and operating member for angular movement together and for angular movement relative to each other about a common axis, abutments on the arms and operating member for limiting relative angular movement between them, torsion springs acting between the arms and operating member to force the abutments together, and an operating mechanism acting upon the operating member at a point spaced from the said axis, for moving the operating member and arms bodily about the said axis to engage the hooks in the plate recesses and operable for further moving the operating member to separate the said abutments and apply pressure through the torsion springs to the hook arms.

4. In a printing plate cylinder, plate clamping mechanism comprising a plurality of clamping units for holding the straight edge of a plate, each unit comprising a hook arm for engaging in a recess in the underside of a plate, an operating member, a shaft mounting the hook arm and operating member for angular movement together and for angular movement relative to each other about a common axis, abutments on the arm and operating member for limiting relative angular movement between them, a torsion spring acting between the arm and operating member to force the abutments together, and an operating mechanism acting upon the operating member at a point spaced from the said axis, for moving the operating member and hook arm bodily about the said axis to engage the hook in a plate recess and operable for further moving the operating member to separate the said abutments and apply pressure through the torsion spring to the hook arm, and also engaging the operating member for moving it and the hook arm bodily about the said axis, to retract the same to a plate releasing position.

5. Plate clamping mechanism according to claim 4, in which the operating member has a plate dislodging projection extending above the cylinder surface in the said plate releasing position for dislodging a plate, and retracted below the cylinder surface in plate clamping position.

6. In a printing plate cylinder, a plate clamping mechanism comprising spring urged clamps for engaging in recesses under a plate adjacent one straight edge thereof, and cooperating clamping means for engaging in recesses under the other straight edge of the plate, the last said clamping means comprising a bar carrying a pair of clamping hooks, a member having a surface disposed chordwise of the cylinder and supporting the bar for sliding and pivotal movement, an adjusting screw and a pivotal connection between the adjusting screw and the central part of the bar, whereby the said bar may be adjusted chordwise and may pivot for engaging the hooks carried thereby in recesses out of alignment with the cylinder axis.

7. Plate clamping mechanism according to claim 6, in which the said pivotal connection comprises a poppet member receiving the adjusting screw in a threaded bore and rotatably carrying the bar.

References Cited in the file of this patent UNITED STATES PATENTS 1,350,488 Blaine Aug. 24, 1920 2,496,200 Crafts Jan. 31, 1950 2,639,668 Chase et a1. May 26, 1953 2,681,007 Harless June 15, 1954 2,732,798 Chase Jan. 31, 1956 FOREIGN PATENTS 682,819 Great Britain Nov. 19, 1952 

